Fix shutdown of LXC controller

Since we are not yet using the virNetServerPtr object for running
the event loop, we can't use virNetServerQuit(). Instead set the
global 'quit' flag in libvirt_lxc

src/lxc/lxc_controller.c

@@ -852,8 +852,11 @@ static void virLXCControllerSignalChildIO(virNetServerPtr server ATTRIBUTE_UNUSE
     int ret;
 
     ret = waitpid(-1, NULL, WNOHANG);
-    if (ret == ctrl->initpid)
-        virNetServerQuit(ctrl->server);
+    if (ret == ctrl->initpid) {
+        virMutexLock(&lock);
+        quit = true;
+        virMutexUnlock(&lock);
+    }
 }